It is generally known that poultry such as chickens, geese, turkeys, quail, pheasants and the like are particularly susceptible to poor productivity (reduced growth rate, feed efficiency, egg shell quality and high mortality) during periods of environmental heat distress (high ambient temperatures and high relative humidity). It is also generally well known that these heat distress effects are greatly exacerbated if the anticoccidial agent nicarbazin (Nicarb) is administered during such heat distress periods.
Heat distress substantially reduces the growth rate of broiler chicks. Diets have been altered to reduce this problem via reducing the heat increment of the diet with fat supplementation (H. L. Fuller et al; "Effect of Heat Increment of the Diet on Feed Intake and Growth of Chicks Under Heat Stress", Proc. Maryland Nutr. Conf., pp 58-664, 1973) and improved the amino acid balance (P. W. Waldroup et al; "Performance of Chicks Fed Diets Formulated to Minimize Excess Levels of Essential Amino Acids", Poultry Sci., 55:243-253, 1976). It has also been suggested that the decline in growth rate results directly from reduced feed intake (R. L. Squibb et al; "Growth and Blood Constitutients of Immature New Hampshire Fowl Exposed to Constant Temperatures of 99.degree. C. for 7 Days", Poultry Sci., 38:220-221, 1959). It has been demonstrated that the growth rate of heat stressed broilers can be increased by force feeding at a level exceeding ad libitum feed intake (M. O. Smith et al; "Feed Intake and Environmental Temperature Effects Upon Growth, Carcass Traits, Ration Digestibility, Digestive, Passage Rate and Plasma Parameters in Ad Libitum and Force-Fed Broiler Chicks" Poultry Sci., 62:1504 abstr., 1983).